JP2007008678A - Belt conveyance device in image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt conveyance device in an image forming device capable of accurately preventing meandering and oblique advancement by a simple constitution without giving bad influence to an image to be formed and a belt itself. <P>SOLUTION: The belt conveyance device in the image forming device is provided with a plurality of rollers and an endless-like belt suspended and tensionaly provided between the rollers and rotated. A roller portion in one of the rollers is divided to a plurality of portions and a periphery speed of the divided roller at a central part is made faster than a periphery speed in the other divided roller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photoreceptor belt, an intermediate transfer belt, a recording medium conveyance belt, or a fixing belt in a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine using the electrophotographic method. The present invention relates to an endless belt conveyance device, and more particularly to a belt conveyance device in an image forming apparatus that prevents skewing of an endless belt.

  Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, for example, as shown in FIG. 3 as a tandem color image forming apparatus, a photoconductor The intermediate transfer belt 2 for transferring the toner image formed on 1 or the fixing device 26 for fixing the toner image transferred on the recording medium 27 as shown in FIG. For example, a fixing belt 31 for pressing the recording medium 27 against the fixing roller 30, a photosensitive belt having a photosensitive member in a belt shape, a recording medium conveying belt for conveying the recording medium from a recording medium cassette to a transfer position, and the like. Endless belts are used in various parts.

  In FIG. 3, reference numeral 1 denotes a photosensitive member formed in a drum shape corresponding to each color of cyan, magenta, yellow, and black. A charging device 3 such as a scorotron and exposure 4 are performed around the photosensitive member 1. An unillustrated exposure device, a developing device 5, a cleaning device 6 for cleaning toner remaining after the toner image on the photoreceptor 1 is transferred to the intermediate transfer belt 2, and a charge remaining on the photoreceptor 1 are removed. The static eliminator 7 and the like are arranged to form a process unit, and the process unit is arranged in the traveling direction of the intermediate transfer belt 2, and the toner image formed on the photosensitive member 1 is primarily transferred to superimpose colors. This is a tandem type color image forming apparatus that further transfers the formed full color image to the recording medium 27 secondarily.

  The intermediate transfer belt 2 is suspended from a pair of driven and driven rollers 21 and 22 and a backup roller 23. On the intermediate transfer belt 2, the above-described black, Photosensitive members 1 that are image carriers for cyan, magenta, and yellow are arranged side by side, and the primary transfer roller 8 is arranged so as to face each other with the intermediate transfer belt 2 interposed therebetween. Has been placed. Reference numeral 25 denotes a secondary transfer roller for transferring the primary transferred and color-superposed toner image to the recording medium 27. The toner remaining on the intermediate transfer belt 2 without being transferred to the recording medium 27 is cleaned. It is cleaned by the device 24 and prepared for the next image formation.

  In FIG. 2, 30 is a fixing roller, 31 is a fixing belt, 32 and 33 are driven rollers, 34 is a heater, 37 is an offset prevention coating, and the recording medium 27 sent to the fixing roller 30 by the fixing belt 31. The fixing is performed by the heat of the heater 34 provided on the fixing roller.

  Such endless belts such as the fixing belt 31, the intermediate transfer belt 2, the recording medium conveyance belt, and the photosensitive belt are driven by being suspended from, for example, driving rollers and driven rollers 21, 22, and 23. Thickness, dimensional accuracy, processing accuracy and parallelism of the suspended roller, positional imperfections such as tension, imbalance and runout of tension, and non-uniformity of the heat rollers 32 and 33 used for fixing in the fixing belt 31 Due to a difference in partial expansion coefficient due to the propagation, a displacement in the belt width direction perpendicular to the belt conveyance direction, that is, meandering or skewing occurs.

  However, when such meandering or skewing occurs, for example, the transfer position of the intermediate transfer belt 2 is shifted to the left or right. In particular, the full color toner is formed by superimposing colors on the intermediate transfer belt 2. In a tandem color image forming apparatus that obtains an image, such a color misregistration becomes a serious problem.

  In addition, in other endless belts, such meandering and skewing may cause damage to the belt end face, and in severe cases, an accident may occur such as the belt itself being broken. In order to prevent such an accident, it is only necessary to increase the accuracy of the parallelism and runout between the rollers where the endless belt is suspended. It also leads to a cost increase.

  Therefore, for example, as shown in FIG. 4, a method of providing a flange 44 on the shaft 42 of the roller portion 43 in the suspension roller 41 of the belt 40, as shown in Patent Document 1 and as shown in FIG. 5, for example, the outer periphery of the belt 50. A guide member 50a for restricting the meandering of the belt is provided on the surface side or the inner peripheral surface side, and the meandering and skewing are regulated by contacting both ends of the roller portion 53 of the roller 51 provided on the shaft 52 and other members. 6, a method of changing the outer diameter of the roller 61 for suspending the belt 60 in the direction of the shaft 62 as shown in FIG. 6, and forming a Tyco shape 63, as shown in Patent Document 2 and as shown in FIG. In addition, the suspension roller 71 that substantially abuts in the width direction perpendicular to the traveling direction of the belt 70 is moved 71a by the displacement means 72 in accordance with the force accompanying the movement (meandering or skewing) of the belt 70 in the width direction. Indicated by By tilting the rotation axis as, serpentine, or a method for correcting the skew it has been proposed.

Japanese Utility Model Publication No. 5-75246 JP 2001-080782 A

  However, the flange 44 is provided at the end of the suspension roller 41 of the belt 40 as shown in FIG. 4, or the guide members 50a are provided at both ends of the inner peripheral surface of the belt 50 as in Patent Document 1 and FIG. Although there is an effect of preventing meandering, a large load is applied to the contact portion between the end portion of the belt 40 and the flange 44 and the contact portion between the guide member 50a and the end portion of the roller 53. There are problems such as breakage, accuracy and cost related to parts processing. Further, as shown in FIG. 6, the method of changing the outer diameter of the roller 61 that suspends the belt 60 in the axial direction to obtain the Tyco shape 63 makes it difficult to ensure accuracy in terms of shape. Only rubber belt materials with softness, elasticity, and thickness that can be adapted can be used, and problems with belt durability due to constant load on the shape, and generally used for intermediate transfer belts There is also a problem that deformation occurs when an image is transferred without using a base material using a polyimide resin, and accurate transfer becomes difficult.

  Furthermore, the method of correcting the meandering by tilting the rotating shaft of the suspension roller 71 according to the force accompanying the movement in the width direction of the belt 70 shown in Patent Document 2 in FIG. Since the basic position accuracy is difficult to obtain because the reference position of the roller is not determined, and the belt continues to be transported with the roller rotating shaft tilted in position, there are large individual differences and machine differences that are not product-friendly. There are problems such as high possibility of stability.

  Therefore, it is an object of the present invention to provide a belt conveying device in an image forming apparatus that can prevent meandering and skewing with a simple configuration and without adversely affecting an image to be formed and the belt itself. .

In order to solve the above problems, a belt conveying device in an image forming apparatus according to the present invention is provided.
A belt conveying device in an image forming apparatus comprising a plurality of rollers and an endless belt that is suspended and rotated between the rollers,
A roller portion of one of the plurality of rollers is divided into a plurality of portions, and a first gear provided at an end of the divided roller at the center of the divided rollers is adjacent to the first gear. The second gear provided at the end of at least one other divided roller is connected to the adjacent first and second gears so that the peripheral speed of the central divided roller is faster than the peripheral speed of the other divided roller. A third gear having a gear ratio is provided, and the roller peripheral speed at the center is faster than the peripheral speeds of the other rollers.

  In this way, by configuring the belt conveyance device so that the peripheral speed of the roller at the center is faster than the peripheral speed of the other rollers, a force in the direction toward the center always acts on the belt, and a very simple configuration Thus, it is possible to provide a belt conveying device in an image forming apparatus capable of suppressing belt meandering and skewing.

  And by having constituted in this way, the same effect as the roller which changed the outside diameter in the above-mentioned axial direction and made it into a Tyco shape is acquired, but making the above-mentioned plurality of divided roller outside diameters the same outside diameter Thus, it is possible to provide a belt conveying device in an image forming apparatus that does not cause various problems that have occurred in the above-described Tyco roller and does not adversely affect the image to be formed or the belt itself.

  In addition, a mechanism for transmitting a driving force to the roller shaft divided into the plurality of divided rollers is provided, and at least one of the divided plurality of divided rollers is fixed to the roller shaft, so that the divided rollers are attached to the belt. As a driving roller, the force that moves the belt toward the center becomes stronger, and a greater effect can be obtained.

  Further, the endless belt that is suspended and rotated between the rollers is made of a base material made of resin, so that, for example, when this belt is an intermediate transfer belt, the toner image formed on the photosensitive member can be reliably transferred. A belt conveying device capable of transferring can be obtained.

  As described above, according to the present invention, it is possible to provide a belt conveyance device in an image forming apparatus that can prevent meandering and skewing with a simple configuration and without adversely affecting an image to be formed or the belt itself. it can.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a diagram showing a schematic configuration when a belt conveying device in an image forming apparatus according to the present invention is applied to the fixing belt conveying device of the fixing device shown in FIG. 2 as an example, and FIG. FIG. 3 is a diagram illustrating a schematic configuration of a tandem color image forming apparatus as an example of an image forming apparatus having the fixing device illustrated in FIG. 2. In the following description, the case where the present invention is applied to a fixing belt conveyance device of a fixing device will be described as an example. However, the present invention is not limited to a photosensitive belt, an intermediate transfer belt, and a recording medium conveyance belt. It is obvious that it can be applied to a belt conveying device.

  First, the configuration and operation of an image forming apparatus to which the present invention is applied will be briefly described with reference to FIG. 3. As described above, this image forming apparatus is generally used for color image forming apparatuses such as cyan, magenta, and yellow. A tandem type color image forming apparatus in which process units including a photoreceptor 1 formed in a drum shape corresponding to each color of black are arranged in a traveling direction of the intermediate transfer belt 2 and provided corresponding to each color. Around the photosensitive member 1, a charging device 3 such as a scorotron, an exposure device (not shown) for performing exposure 4, a developing device 5, and a toner remaining after transferring a toner image on the photosensitive member 1 to an intermediate transfer belt A cleaning device 6 for cleaning the toner, a static eliminator 7 for neutralizing charges remaining on the photosensitive member 1, and the like, and further, the photosensitive member 1 with the intermediate transfer belt 2 interposed therebetween. The primary transfer roller 8 is arranged to face.

  The intermediate transfer belt 2 is for primary transfer of the toner image formed on the photosensitive member 1 to superimpose colors, and further to secondary transfer the formed full color image to the recording medium 27. An image for each color of black, cyan, magenta, and yellow is stretched around the driven rollers 21 and 22 and the backup roller 23, and is in contact with the intermediate transfer belt 2 on the intermediate transfer belt 2. Photoconductors 1 that are carriers are arranged side by side.

  The developing devices 5 arranged around the photoreceptors 1 are filled with black toner, cyan toner, magenta toner, or yellow toner, and toner images of the respective colors are formed by a known electrophotographic method. The That is, each photoconductor 1 is uniformly charged to a predetermined polarity by the charging device 3, and by performing exposure 4 with light based on predetermined image information, the potential of the light irradiating portion is lowered to form a latent image. . A toner image is formed by supplying toner of each color to the formed latent image with a developing device 5 under a predetermined developing bias.

  The formed toner image of each color is an intermediate transfer belt driven in the direction of the arrow in FIG. 3 by a primary transfer roller 8 to which a primary transfer bias potential (a polarity opposite to the toner charging polarity) is applied. 2 is sequentially transferred and overlaid with a color to form a full-color toner image. The full-color toner image is further transferred to a recording medium (paper) 27 conveyed between the secondary transfer roller 25 and the backup roller 23, and a secondary transfer bias having a polarity opposite to that of the toner image applied to the secondary transfer roller 25. The recording medium (paper) is further sent to the fixing device 26 to fix the toner image.

  Further, the toner remaining without being primarily transferred from the photoreceptor 1 to the intermediate transfer belt 2 is removed by the cleaning device 6, and the charge remaining on the photoreceptor 1 is removed by the charge eliminator 7, while the secondary transfer is performed. The toner remaining on the intermediate transfer belt 2 later is cleaned by the cleaning brush 24 to prepare for the next image formation.

  Among them, the fixing device 26 has a heater 34 inside and a surface covered with an offset prevention coating 37 in order to fix the toner image on the recording medium 27 shown in FIG. 3 as shown in FIG. The roller 30 and a fixing belt 31 that is suspended from, for example, driven rollers 32 and 33 and presses the recording medium 27 that has been transferred by transferring the toner image against the fixing roller 30.

  The fixing roller 30 is heated by a built-in heater 34 and rotated while being held at a constant temperature, and the fixing roller 30 is driven by the arrangement position of the driven rollers 32 and 33 or by a pressing force such as a spring (not shown). The fixing belt 31 that is biased by the rotation of the fixing belt 31 is rotated by the frictional force and at the same time the temperature of the fixing belt 31 is raised by heat transfer from the fixing roller 30. Therefore, when the recording medium 27 on which an unfixed image (not shown) is formed is provided at the nip portion between the fixing roller 30 and the fixing belt 31, the toner constituting the unfixed image is melted and pressed to fix the image on the recording medium 27. Is done.

  In the fixing device configured as described above, for example, the driven roller 32 that suspends the fixing belt 31 is provided with a plurality of the same diameter on the roller shaft 32a as shown in FIG. 1 (in the example of FIG. 4). The divided rollers 32b, 32c, and 32d are divided into three), and each of the divided rollers 32b, 32c, and 32d has a second gear indicated by 32e on the side of the divided roller 32b at the center of the divided rollers 32c. Similarly, a second gear indicated by 32h is provided on the side of the central roller 32d of the split roller 32d, and a first gear indicated by 32f and 32g is provided on both ends of the central roller 32c. The first and second gears have gears 35a and 35b and are connected to the gears 32e and 32f. The third gear 35 has gears 36a and 36b and is connected to the gears 32g and 32h. They are connected respectively same with the third gear 36.

  Further, the gears 35a and 35b and the gears 36a and 36b in the third gears 35 and 36 are the second gear 32e, the first gear 32f, the second gear 32h, and the first gear which are engaged with each other. The gear ratio with the gear 32g is set so that the peripheral speed of the central split roller 32c is faster than the peripheral speed of the split rollers 32b and 32d on both sides.

  That is, for example, when the pitch of each gear is the same, the diameters of the first gears 32f and 32g are made smaller than the second gears 32e and 32h, and the diameters of the gears 35b and 36b are made larger than the gears 35a and 36a. Thus, when the fixing belt 31 is rotated by the rotation of the fixing roller 30, the peripheral speed of the central divided roller 32c is faster than the divided rollers 32b and 32d on both sides.

  For example, the number of teeth of the second gears 32e and 32h provided on the divided rollers 32b and 32d on both sides is 51, the number of teeth of the first gears 32f and 32g provided on both sides of the central divided roller 32c is 50, When the number of teeth of the gears 35a and 35b and the gears 36a and 36b in the third gear 35 and 36 is 49/50, when the rotation number of the central division roller 32c is N, the rotation of the division rollers 32b and 32d on both sides The number is 0.96 × N, which is about 4% slower than the central divided roller 32c.

  Therefore, there is provided a belt conveyance device in an image forming apparatus in which a force in a direction toward the center always acts on the fixing belt 31 and can suppress meandering and skewing of the belt with a very simple configuration. Can do. Further, this effect is the same as that obtained by the Tyco-shaped roller 61 shown in FIG. 6, but since the divided rollers 32b, 32c, and 32d have the same outer diameter, the Tyco-shaped roller 61 is adopted. It is difficult to ensure the accuracy of the shape that occurs in some cases, only a rubber belt material with softness, elasticity, and thickness that can be adapted to the roller shape as a belt can be used, and a geometrical load is always applied Therefore, there is no problem of durability of the belt due to the above, or a problem that deformation occurs when an image is transferred without using a polyimide resin substrate generally used for an intermediate transfer belt, and accurate transfer becomes difficult. .

  In the above description, the divided rollers 32b, 32c, and 32d have been described as being freely rotatable on the roller shaft 32a. However, a mechanism for transmitting a driving force to the roller shaft 32a is provided to divide the divided rollers 32b, 32c, and 32b. When at least one (preferably the central 32c split roller) of 32d is fixed to the roller shaft, this split roller becomes a driving roller for the belt, and the force that moves the belt toward the center becomes stronger, thereby obtaining a greater effect. be able to.

  Further, when the present invention is applied to an intermediate transfer belt, the toner image formed on the photoreceptor 1 can be reliably transferred by using a base material made of a polyimide resin that has been conventionally used. Further, the tension applied to the belt, the process peripheral speed, and the like are different in the system configuration, the material of the divided rollers 32b, 32c, and 32d, the first and second gears 32e to 32h, And the gear ratio by 35a, 35b, 36a, 36b constituting the third gear is appropriately set, and the balance between the frictional force and the sliding force between the belt and the split roller, that is, the force to bring the belt toward the center side is optimized. Thus, the effect of the present invention can be further increased.

  In the above description, the first and second gears have been described as being provided on each of the central split roller 32c and the split rollers 32b and 32c on both sides. For example, the split rollers 32b and 32c on both sides are provided on the shaft 32a. The first split gear 32c is fixed to the shaft 32a so that the central split roller 32c is rotatable about the shaft 32a. The first gear is provided only on one end side, and the first split gear 32b or 32c on the side where the first gear is provided. Even if two gears are provided, the same effect can be obtained.

  According to the present invention, it is possible to provide a belt conveying device that can prevent meandering and skewing with a simple configuration without adversely affecting an image to be formed and the belt itself, and can be provided with a high quality by being applied to the image forming device. It is possible to provide an image forming apparatus capable of forming a simple image over a long period of time.

1 is a diagram illustrating a schematic configuration of a belt conveyance device in an image forming apparatus according to the present invention. 1 is a schematic configuration diagram of a fixing belt conveyance device of a fixing device to which the present invention is applied as an example. 1 is a schematic configuration diagram of a tandem type color image forming apparatus as an example of an image forming apparatus. It is the schematic of the technique which provides a flange at the both ends of the roller which suspends a belt, and prevents meandering and skewing of a belt. It is the schematic of the technique which provides a guide member in a belt and contact | abuts to the both ends of a roller, and prevents meandering and skewing of a belt. It is the schematic of the technique which forms the roller which suspends a belt in a Tyco shape, and prevents meandering and skewing of a belt. It is the schematic of the technique which inclines the rotating shaft of the roller which suspends a belt, and prevents meandering and skewing.

Explanation of symbols

30 fixing roller 31 fixing belt 32, 33 driven roller 32a roller shaft 32b, 32c, 32d split roller 32f, 32g first gear 32e, 32h second gear 34 heater 35, 36 third gear 35a, 35b, 36a, 36b Gear 37 constituting third gear Offset prevention coating

Claims (4)

A belt conveying device in an image forming apparatus comprising a plurality of rollers and an endless belt that is suspended and rotated between the rollers,
A roller portion of one of the plurality of rollers is divided into a plurality of portions, and a first gear provided at an end of the divided roller at the center of the divided rollers is adjacent to the first gear. The second gear provided at the end of at least one other divided roller is connected to the adjacent first and second gears so that the peripheral speed of the central divided roller is faster than the peripheral speed of the other divided roller. And a third gear having a gear ratio as described above, wherein the peripheral speed of the roller at the center is faster than the peripheral speed of the other rollers.   The belt conveying device in the image forming apparatus according to claim 1, wherein the plurality of divided roller outer diameters have the same outer diameter.   The mechanism for transmitting a driving force to a roller shaft divided into the plurality of divided rollers is provided, and at least one of the divided plurality of divided rollers is fixed to the roller shaft. Belt conveying device in the image forming apparatus.   4. A belt conveying apparatus in an image forming apparatus according to claim 1, wherein the endless belt that is suspended and rotated between the rollers has a base material made of resin.

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